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The C-terminal domain is sufficient for endonuclease activity of Neisseria gonorrhoeae MutL

Duppatla, Viswanadham and Bodda, Chiranjeevi and Urbanke, Claus and Friedhoff, Peter and Rao, Desirazu N (2009) The C-terminal domain is sufficient for endonuclease activity of Neisseria gonorrhoeae MutL. In: Biochemical Journal, 423 (Part 2). pp. 265-277.

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The mutL gene of Neisseria gonorrhoeae has been cloned and the gene product purified. We have found that the homodimeric N. gonorrhoeae MutL (NgoL) protein displays an endonuclease activity that incises covalently closed circular DNA in the presence of Mn2+, Mg2+ or Ca2+ ions, unlike human MutL alpha which shows endonuclease activity only in the presence of Mn2+. We report in the present paper that the C-terminal domain of N. gonorrhoeae MutL (NgoL-CTD) consisting of amino acids 460-658 exhibits Mn2+-dependent endonuclease activity. Sedimentation velocity, sedimentation equilibrium and dynamic light scattering experiments show NgoL-CTD to be a dimer. The probable endonucleolytic active site is localized to a metal-binding motif, DMHAX(2)EX(4)E, and the nicking endonuclease activity is dependent on the integrity of this motif. By in vitro comparison of wild-type and it mutant NgoL-CTD protein, we show that the latter protein exhibits highly reduced endonuclease activity. We therefore suggest that the mode of excision initiation in DNA mismatch repair may be different in organisms that lack MutH protein, but have MutL proteins that harbour the D[M/Q]HAX(2)EX(4)E motif.

Item Type: Journal Article
Publication: Biochemical Journal
Publisher: Portland Press
Additional Information: Copyright for this article belongs to Portland Press.
Keywords: DNA repair; endonuclease; MutL; NgoL; Neisseria gonorrhoeae
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 08 Dec 2009 08:51
Last Modified: 19 Sep 2010 05:52
URI: http://eprints.iisc.ac.in/id/eprint/24963

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